Heavy Metals in Cocoa International Workshop on possible EU regulations on cadmium in cocoa and chocolate products 3rd & 4 th May Jayne Crozier www.cabi.org KNOWLEDGE FOR LIFE
Project Aims To establish the level of heavy metals in cocoa beans from Peru & Venezuela, particularly cadmium, lead & aluminium To increase our knowledge and understanding of the factors which affect the uptake and accumulation of heavy metals in cocoa
Site Selection Countries Peru & Venezuela Sampling regions Three main cocoa producing regions were selected in each country Sampling within each region Ten farms were selected within each region Merida State Aragua State Sucre State
Soil Sampling 10 samples were collected from each farm Sample were taken at six different depths: 0-5cm, 5-10cm, 10-20cm, 20-40cm, 40-60cm & 60-80cm A composite sample was prepared from each depth
Cocoa Bean Sampling 1 or 2 mature pods were collected from trees where the soil samples were taken Composite samples from each farm were prepared and dried in the laboratory Samples were prepared with and without the seed coat Processed (dried and/or fermented) beans were collected from farms and collection centres when available
Farmer Questionnaire To establish baseline data about each farm: Type and size of farm Variety and type of planting material used Management practices use of pesticides & fertilizers Soil types in the region Location - near mining or industrial activities Land use in & around the farm Post harvests processes used
Heavy Metal Analysis Laboratory SERVACO Belgium Soil Total concentrations of Al, As, Cd, Cu, Fe, Pb & Zn were analysed using ICP- OES Available concentrations of Al, As, Cd, Cu, Fe, Pb & Zn were analysed using ICP-MS Cocoa Beans Total concentration of Al, As, Cd, Cu, Fe, Pb & Zn were analysed using ICP-OES All analyses were carried out using standardised accredited methods
Cd concentration of beans from Peru (82 samples) Frequency (direct count) 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 Concentrations ranged from 0.03-2.51 mg/kg 52 samples <0.6 mg/kg (63%) 30 samples >0.6 mg/kg (37%) 0 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Cd mg/kg
Cd concentration of beans from Venezuela (92 samples) 25 Frequency (direct count) 20 15 10 5 Concentrations ranged from 0.03-3.52 mg/kg 74 samples <0.6 mg/kg (80%) 18 samples >0.6 mg/kg (20%) 0 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Cd mg/kg
Cd concentration of beans from Peru & Venezuela Cd mg/kg 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 A A A Peru C Ven E Peru N Ven W Peru S Ven C Country Region A B B Levels for Cd varied by country & region Highest levels of Cd were found in beans from northern & central Peru &, eastern & western Venezuela No differences were found between fresh beans and dried/fermented beans No differences were observed between whole beans and beans with the seed coat removed
Total Cd mg/kg Cd concentration of soil from Peru & Venezuela 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 A A B BC CD D The highest total concentrations of Cd was found in the soils of northern & central Peru Total Cd concentrations were highest in the top layer of soil & decreased with depth Many of the soil samples analysed for available Cd were below the limit of detection (0.04 µg/kg) No differences were observed between country or region for available Cd concentrations 0.1 0.0 Peru N Peru C Peru S Ven E Ven C Ven W Country Region The highest levels of available Cd were found in the upper layers of soil between the depths of 5-20 cm
Correlation results Soil ph was found to be positively correlated with total Cd and negatively correlated with available Cd No relationship was found between Cd and clay or organic matter No relationship with phosphorus could be evaluated as the concentration of phosphorus was below the level of detection in all soil samples Total Cd and Zn concentrations in the soil showed a strong positive relationship as did available Cd and Zn Beans No relationship was found between the Cd content of the beans and the concentration of available Cd in the soil Cd concentrations in the beans were found to be weakly positively correlated with the concentration of total Cd in the soil
Conclusions No differences were observed in the Cd concentrations of fresh and processed beans indicating that contamination did not occur during post-harvest processing The concentration of Cd was not reduced by the removal of the testa suggesting that Cd does not accumulate in the seed coat ph has an effect on the availability of Cd in the soil, as the soil becomes more acidic the availability of Cd increases Cd and Zn are strongly correlated in the soil. It has been reported that when Zn is deficient plants may uptake higher levels of Cd High concentrations of Cd in beans does not appear to be directly related to high concentrations of available Cd in the soil Beans with high concentrations of Cd were found to have grown in soils with low levels of both total and available Cd uptake/accumulation in cocoa may be related to varietal differences
Recommendations Due to the limited nature of the study and the complexity of the results only general recommendations can be given Increase soil ph Increase OM content of soil Avoid use of phosphate fertilizers Avoid irrigation with contaminated water Test for macro and micro nutrient deficiencies Selection of cocoa varieties with low accumulation levels Avoid post harvest contamination
The Ministry of Agriculture, Nature and Food Quality in the Netherlands (LNV), the European Cocoa Association (ECA) & CAOBISCO www.cabi.org KNOWLEDGE FOR LIFE
Thank You Jayne Crozier j.crozier@cabi.org www.cabi.org KNOWLEDGE FOR LIFE